Pulse width modulated (PWM) circuits are used for a variety of purposes. For instance, in automotive or vehicle electronics, PWM drivers are used to communicate both data and commands to and from electronic control modules (ECM).
One type of PWM is known as duty cycle modulation (DCM). In duty cycle modulation, a pulse waveform is transmitted from a source to a destination. The pulse waveform consists of a series of signals having a set period. Each signal includes a pulse. The pulse is defined where the signal is "on", i.e., has a particular value. The duty cycle of each signal is the relationship between the pulse width and the period. The pulse waveform carries data or commands by varying the width, and therefore, the duty cycle of each signal.
PWM drivers are used, for example, to carry data from sensors to an ECM. PWM drivers are generally more accurate than analog circuits because the signals are digital in nature and not as susceptible to noise and other forms of interference. This becomes more apparent when the signals are transmitted over longer distances.
However, in order to be useful, a PWM driver must be very accurate. Thus, typical PWM circuits contain additional components to ensure accuracy. For example, a PWM circuit may contain as many or more as 6 operational amplifiers and/or comparators. As PWM drivers are very useful in automotive or vehicle electronics, there may be quite a few such PWM drivers per vehicle. In order to reduce costs, it is therefore desirable to reduce the number of components.
The present invention is directed to overcoming one or more of the problems, as set forth above.